The present invention generally relates to golf balls, and more particularly, to a golf ball having improved dimple patterns.
Golf balls were originally made with smooth outer surfaces. In the late nineteenth century, players observed that the guttie golf balls traveled further as they got older and more gouged up. The players then began to roughen the surface of new golf balls with a hammer to increase flight distance. Manufacturers soon caught on and began molding non-smooth outer surfaces on golf balls.
By the mid 1900""s, almost every golf ball being made had 336 dimples arranged in an octahedral pattern. Generally, these balls had about 60% of their outer surface covered by dimples. In 1983, Titleist introduced the TITLEIST 384, which had 384 dimples that were arranged in an icosahedral pattern. About 76% of its outer surface was covered with dimples. Today""s dimpled golf balls travel nearly two times farther than a similar ball without dimples.
The dimples on a golf ball are important in reducing drag and providing lift. Drag is the air resistance that acts on the golf ball in the opposite direction from the balls flight direction. As the ball travels through the air, the air surrounding the ball has different velocities and, thus, different pressures. The air exerts maximum pressure at the stagnation point on the front of the ball. The air then flows over the sides of the ball and has increased velocity and reduced pressure. At some point it separates from the surface of the ball, leaving a large turbulent flow area called the wake that has low pressure. The difference in the high pressure in front of the ball and the low pressure behind the ball slows the ball down. This is the primary source of drag for a golf ball.
The dimples on the ball create a turbulent boundary layer around the ball, i.e., the air in a thin layer adjacent to the ball flows in a turbulent manner. The turbulence energizes the boundary layer and helps the boundary layer stay attached to the golf ball""s surface further around the ball to reduce the area of the wake. This greatly increases the pressure behind the ball and substantially reduces the drag.
Lift is the upward force on the ball that is created from a difference in pressure on the top of the ball to the bottom of the ball. The difference in pressure is created by a warpage in the air flow resulting from the ball""s back spin. Due to the back spin, the top of the ball moves with the air flow, which delays the separation to a point further rearward. Conversely, the bottom of the ball moves against the air flow, moving the separation point forward. This asymmetrical separation creates an arch in the flow pattern, requiring the air over the top of the ball to move faster, and thus have lower pressure than the air underneath the ball.
Almost every golf ball manufacturer researches dimple patterns in order to increase the distance traveled by a golf ball. A high degree of dimple coverage is beneficial to flight distance, but only if the dimples are of a reasonable size. Dimple coverage gained by filling spaces with tiny dimples is not very effective, since tiny dimples are not good turbulence generators. Most balls today still have many large spaces between dimples or have filled in these spaces with very small dimples that do not create enough turbulence at average golf ball velocities.
There are many patents directed to various dimple patterns. U.S. Pat. No. 5,046,742 discloses uniformly distributed dimple pattern based upon repeated polygons, hexagons and pentagons. Each polygon having a number of vertices that are connected by a number of edges. The golf ball surface is divided into thirty-two geometric shapes, twelve spherical pentagons and twenty spherical hexagons. Dimples of the same or different sizes can be placed in or on the edges of each pentagon and hexagon. This produces a golf ball that has a high degree of symmetry. This patent does not disclose a dimple pattern that is based upon a repeated polygon formation of dimples that extend from the pole to the equator.
U.S. Pat. No. 5,149,100 discloses a golf ball having a dimple pattern where a number of the dimples are organized in hexagon and pentagon formations. Orientation of these dimple formations on the golf ball""s outer surface is based upon the parting line, two hemispheres, and two poles of the outer surface. The parting line is located at the equator of the outer surface, there by dividing the outer surface into the two hemispheres. Each hemisphere has a pole positioned at the furthest point on the outer surface from the parting line. The golf ball disclosed in the patent has a dimple pattern with a hexagon formation of dimples radiating outwardly from a dimple centered at each pole, and pentagon formations of dimples interposed between the hexagon formation of dimples and the parting line of the golf ball. The patent does not disclose a dimple pattern that is based upon a repeated polygon formation of dimples that extend from the pole to the equator.
Thus, there continues to be a need for dimple patterns that have a high percentage of dimple coverage. More particularly, there is a need for dimple patterns that do not have large spaces between the dimples. Additionally, there is a need for dimple patterns that do not need to fill in large spaces with very small dimples, which do not create sufficient turbulence.
The present invention provides a golf ball with an outer surface that has a plurality of dimples positioned according to a pattern comprising a pole polygon, which has designated edges and vertices, centered at a pole of the golf ball with either translated or mirror-images of polygons connected to it that extend toward a parting line of the golf ball.
The present invention also provides for a method of packing dimples on the outer surface of the golf ball according to the above mentioned pattern of connected polygons.
The dimple patterns according to the present invention have dimples of various sizes that are positioned according to a series of connected polygons that originate from a pole polygon and extend toward the parting line. Because the outer surface of the golf ball is not completely covered by polygons, the dimple patterns of the present invention have some uniformity but also some variance. Preferably, the dimple patterns according to the present invention have dimples that cover more than 70% of the golf ball surface and more preferably greater than 75%. Preferably, the total number of dimples is about 300 to about 500 and at least about 60% of the dimples have a diameter of about 0.10 inches or greater. More preferably, at least about 80% of the dimples have a diameter of about 0.10 inches or greater.
An embodiment of the present invention is a golf ball with a polygon based pattern used to create the dimple pattern on the outer surface. The pattern originates from a polygon centered at a pole of a golf ball and branches out as connected translated or mirror-image polygons extend towards the parting line from each edge or vertex. Extending polygons by translation occurs when the next polygon added to the pattern has the same orientation as the previous polygon. Extending polygons by mirror-imaging occurs when the next polygon added to the pattern incorporates the shared designated edge or vertex as part of its structure. Dimples are positioned on the golf ball surface according to the connected polygon pattern. For any dimples which, if placed on the outer surface, were to intersect the parting line, the polygon that is used to position those dimples is replaced with a set of polygon edges. Depending on the pattern of the connected polygons, each set of polygon edges corresponds to the edges of a polygon that would typically extend from the edge of the connected polygons that is closest to the parting line. These sets of polygon edges allow the pattern to extend towards the parting line while not causing dimples that are placed on the pattern to intersect the parting line. If dimples which, if placed on the outer surface, were to intersect the parting line, the set of polygon edges that is used to position those dimples is eliminated. The dimple pattern is then completed with the positioning of dimples on the remaining non-dimpled portion of the golf ball surface while also not having any dimple that intersect the parting line.
Preferably, this embodiment of the present invention is a golf ball with a hexagon based pattern used to create the dimple pattern. The pattern originates from a hexagon centered at a pole, a pole hexagon, and branches as translated hexagons extend towards the parting line from each edge. The hexagons preferably terminate at the parting line. One way to accomplish this is for each branch of hexagons to terminate with an incomplete hexagon. The dimple pattern is then completed by placing dimples of varying sizes on and around the hexagons.
Another embodiment of the present invention is also a hexagon based pattern. This embodiment is formed with dimples placed on a modified hexagonal pyramid pattern. This pattern occurs by extending translated or mirror-imaged hexagons from each edge of a pole hexagon towards the parting line.
Additional embodiments of the present invention are based upon other polygon patterns. One such embodiment comprises dimples placed upon a golf ball surface at positions that correspond to a pattern extending from edges of a first pole square. Another embodiment is comprised of dimples placed upon a golf ball surface at positions that correspond to a pattern extending from edges of a pole pentagon. It is preferred for dimple surface coverage that the dimples are formed such that there is only one great circle path, i.e., the parting line, that does not intersect any dimples. As with the other embodiments, this dimple pattern extends towards the parting line and has no dimples that intersect or cross the parting line.
Further, features and advantages of the invention can be ascertained from the following detailed description that is provided in connection with the drawings described below.